Field metabolic rate and water turnover of the numbat (<Emphasis Type="Italic">Myrmecobius fasciatus</Emphasis>)

The numbat (Myrmecobius fasciatus) is a diurnal and exclusively termitivorous marsupial. This study examines interrelationships between diet, metabolic rate and water turnover for wild, free-living numbats. The numbats (488±20.8 g) remained in mass balance during the study. Their basal metabolic rate (BMR) was 3.6 l CO₂ day^–1, while their field metabolic rate (FMR) was 10.8±1.22 l CO₂ day^–1 (269±30.5 kJ day^–1). The ratio FMR/BMR was 3±0.3 for numbats. We suggest that the most accurate way to predict the FMR of marsupials is from the regression log FMR=0.852 log BMR+0.767; (r²=0.97). The FMR of the numbat was lower than, but not significantly different from, that of a generalised marsupial, both before (76%) and after (62–69%) correction for the significant effect of phylogeny on FMR. However the numbat's FMR is more comparable with that of other arid-habitat Australia marsupials (98–135%), for which the regression relating mass and FMR is significantly lower than for nonarid-habitat marsupials, independent of phylogeny. The field water turnover rate (FWTR) of free-living numbats (84.1 ml H₂O day^–1) was highly correlated with FMR, and was typical (89–98%) of that for an arid-habitat marsupial after phylogenetic correction. The higher than expected water economy index for the numbat (FWTR/FMR=0.3±0.03) suggests that either the numbats were drinking during the study, the water content of their diet was high, or the digestibility of their termite diet was low. Habitat and phylogenetic influences on BMR and FMR appear to have pre-adapted the numbat to a low-energy termitivorous niche.Abbreviations BMR basal metabolic rate - FMR field metabolic rate - EWL evaporative water loss - FWTR field water turnover rate - MR metabolic rate - PVR phylogenetic vector regression - RER respiratory exchange ratio - T_a ambient temperature - T_b body temperature - TBW total body water - CO₂ rate of carbon dioxide production - O₂ rate of oxygen consumption - WEI water economy index - WER water efflux rate - WIR water influx rateCommunicated by I.D. Hume     

Cuticular permeability of two species of Coptotermes Wasmann (Isoptera: Rhinotermitidae)

Cuticular permeability (CP) values of worker and soldier castes of Coptotermes formosanus Shiraki and Coptotermes vastator Light were determined using gravimetric techniques. Comparisons were made between castes, species, and between colonies of C. formosanus and C. vastator. CP values did not differ among either species or colony, however they did differ between castes. Data reported here and that of established data in the literature for C. formosanus are inconsistent, with the current report having values as small as half that of previously published data. Examining mean CP data by colony indicated that there is a range for Coptotermes spp. termites, from 6.84+/-1.2 to 25.61+/-1.49 microg H(2)Ocm(-2)mmHg(-1)h(-1) dependent upon caste. A novel method of examining intercaste CP variability is the use of worker:soldier CP ratios. Ratios for C. formosanus were consistent between the current study and previous reports. Mean percentage total body water (%TBW) lost at the time of death was 33.75+/-1.15% (soldiers) and 54.24+/-1.43% (workers) for C. formosanus, and 37.69+/-3.31% (soldiers) and 52.87+/-3.65% (workers) for C. vastator. Consistently, %TBW (and fresh mass) was greater in worker than in soldier castes. These data suggest the use of water storage mechanisms in worker termites, as shown for other rhinotermitids.     

Composition and energy density of eggs from two species of freshwater turtle with twofold ranges in egg size

Lipid, protein, ash, carbohydrate and water content and energy density of eggs were measured from different clutches over a range of egg size in two species of freshwater turtle. Dry egg contents consisted of protein (54-60%), lipid (25-31%) and ash (5-6%) while carbohydrate was found to be negligible (<1%). Albumen consisted principally of water ( approximately 98%), and the dry component was composed of protein (47-51%), ash (19-26%) and lipid (18-21%), but contributed only a small amount ( approximately 2%) to overall dry egg contents. Energy density of dry albumen (15-17 kJ/g) was significantly lower than for dry yolk (26-27 kJ/g). Yolk consisted of 62-70% water, and the dry component was composed of protein (54-61%), lipid (25-31%) and ash (5-6%). Fractional concentrations of water, lipid, protein and ash and energy density remained constant over the range of egg size in Emydura signata eggs. In contrast, an increase in the yolk to albumen ratio and a decrease in water content of yolk as egg size increased caused the composition and energy density of Chelodina expansa eggs to vary systematically with egg size.     

Blood-sucking bugs as a gentle method for blood-collection in water budget studies using doubly labelled water

During doubly-labelled water (DLW) experiments, blood collection by venous puncture may traumatize animals and consequently affect the animals' behaviour and energy budget. Recent studies have shown that blood-sucking bugs (Triatominae; Heteroptera) can be used instead of conventional needles to obtain blood from animals. In this paper, we validate the bug method in captive nectar-feeding bats, Glossophaga soricina, for water budget analysis by comparing the daily water flux estimated with the DLW method with values measured by an energy balance method. As the mean daily water flux of the DLW method was not significantly deviating from the expected value, blood-sucking bugs may substitute more invasive methods of blood collection in DLW experiments. Based on the DLW estimates, daily energy and water intake rates were calculated and compared to values measured with the energy balance method. The DLW method and the energy balance method yielded on average similar results regarding the daily energy intake (DLW method: 48.8+/-14.2 kJ d(-1) versus energy balance method: 48.1+/-9.9 kJ d(-1)) and daily water intake (DLW method: 13.7+/-2.4 mL d(-1) versus energy balance method: 14.7+/-3.0 mL d(-1)). Based on the calculated water and sugar intake per day, we estimated the sugar concentration of ingested nectar to equal on average 16.2+/-2.4% (mass/mass), which fell close to the measured sugar concentration of 17% (mass/mass) bats fed on during the experiment. We conclude that it is possible to extrapolate mean daily energy and water intake for animal groups, populations and species based on DLW estimates, but due to the large variance of results (low accuracy), it seems inadequate to calculate values for single individuals.     

Behavioural and toxic effects of termite defensive secretions on ants

ABSTRACT. The toxicity and biological activity of the defensive secretions of ten species of neotropical termites were examined by bioassay on two species of predatory ant. Pseudomyrmex termitarius (F. Smith) (Pseudomyrmecinae) was more susceptible to the effects of the secretions than Ectatomma sp. (Ponerinae). The bioassay results show a progression in the nature of termite chemical weaponry and in the potency of defensive secretions. The tacky secretions used by Coptotermes and Ruptitermes are simply adhesive, entangling agents with no apparent toxic or pheromonal properties. The secretion of Syntermes calvus Emerson serves as a wound-active poison with little topical activity, while those of Armitermes spp. are repellent to ants and show activity as topical poisons. The secretions used by Nasutitermes spp. combine adhesive, entangling properties with the toxicity of a topically-active poison, and are effective also as ant-repellents.     

Tunnel specificity and forager movement in subterranean termites (Isoptera: Rhinotermitidae and Termitidae)

The movement of foragers of two species of Australian, subterranean, mound-building termites, Coptotermes lacteus (Froggatt) (Rhinotermitidae) and Nasutitermes exitiosus (Hill) (Termitidae), was investigated in their natural habitat using artificial feeding sites along trenches dug to mimic natural forager tunnels that radiate out from the central mound-nests. Termites were dyed by self-feeding on cardboard soaked with histological fat-stains on one or two trenches and then termites were collected from other feeding sites at two and four weeks after the fat-stains were placed. At two and four weeks after marking commenced, 60-75% of marked termites were found in trenches containing the marked paper, and 2-16% were found in trenches on the opposite side of the nest. The proportion of marked termites in a sample was three to eight times greater in the trenches containing the marked paper relative to other trenches. Although difficulties with fat-stains used as markers might explain some of the observed patterns, it is evident that C. lacteus and N. exitiosus foragers do not move randomly between feeding sites in their natural habitat.     

Pyruvate and acetate metabolism in termite mitochondria

Intact mitochondria have been successfully prepared from body tissues from the termites Nasutitermes walkeri and Coptotermes formosanus. This is the first report of the successful isolation of mitochondria from termites (Isoptera: Termitidae). Using an oxygen electrode, oxygen consumption by the mitochondria during the oxidation of various respiratory substrates was determined and their properties measured in terms of respiratory control index and ADP/O. ADP/O was as expected for substrates such as pyruvate, acetylcarnitine and acetyl-CoA and carnitine. Pyruvate and acetate were the major respiratory substrates in both species. The total activity of the pyruvate dehydrogenase complex (PDHc) in the mitochondria from N. walkeri and C. formosanus was determined to be 72.87+/-8.98 and 8.29+/-0.42 nmol/termite/h, respectively. Mitochondria isolated in the presence of inhibitors of PDHc interconversion were used to determine that about 60% of the PDHc was maintained in the active form in both N. walkeri and C. formosanus. The sufficient PDHc activity and high rate of pyruvate oxidation in mitochondria from N. walkeri suggest that pyruvate is rapidly metabolised, whereas the low mitochondrial PDHc activity of C. formosanus suggests that in this species more pyruvate is produced than can be oxidised in the termite tissues.     

布迪椰子不同器官热值的季节变化研究

对布迪椰子的幼叶、成熟叶、叶柄和根在不同季节的干重热值、去灰分热值和灰分含量进行了研究,结果表明:干重热值四个季节的平均值为成熟叶(20.65kJg-1)>幼叶(19.84kJg-1)>根(19.55kJg-1)>叶柄(18.77kJg-1),秋季的干重热值明显高于其它三个季节的干重热值,冬季的干重热值最低,去灰分热值与干重热值的变化趋势基本相同。灰分含量四个季节的平均值为根(5.14%)>叶柄(4.33%)>幼叶(4.21%)>成熟叶(3.97%)。成熟叶的灰分含量一直维持在比较低的水平,而幼叶的在秋季明显下降,在冬季明显上升,幼叶灰分含量的季节变化趋势与成熟叶的相同,叶柄灰分含量在冬季明显低于根部。布迪椰子这种不同器官在不同季节的热值和灰分的变化规律显示其具有较强的耐寒适应性。     

The nutritional value of invertebrates with emphasis on ants and termites as food for mammals

Water, ash, total nitrogen and fat contents were determined for the worker and soldier castes of nine species of central Brazilian termites. These values were then compared with those from other species of termites, ants and 22 other species of terrestrial invertebrates. In comparison with most other invertebrates, termite workers and soldiers tend to be high in ash, low in fat and about equal in water and nitrogen. In contrast, alate ants and termites and most larval or pupal insects have much higher percentages of fat. It is pointed out that most protein and total energy values for arthropods are of limited use because the assays used incorporate the nitrogen present in the indigestible chitin exoskeleton.
It is concluded that most invertebrate-eating mammals choose prey based on availability and other aspects of prey biology and not on gross nutritional factors. The problems associated with eating ants and termites are discussed and include low nutritional value of prey, small prey size and forms of defense relying on the sociality of the prey.     

Nectar quality affects ant aggressiveness and biotic defense provided to plants

Ant–plant mutualisms are useful models for investigating how plant traits mediate interspecific interactions. As plant‐derived resources are essential components of ant diets, plants that offer more nutritious food to ants should be better defended in return, as a result of more aggressive behavior toward natural enemies. We tested this hypothesis in a field experiment by adding artificial nectaries to individuals of the species Vochysia elliptica (Vochysiaceae). Ants were offered one of four liquid foods of different nutritional quality: amino acids, sugar, sugar + amino acids, and water (control). We used live termites (Nasutitermes coxipoensis) as herbivore competitors and observed ant behavior toward them. In 88 hr of observations, we recorded 1,009 interactions with artificial nectaries involving 1,923 individual ants of 26 species. We recorded 381 encounters between ants and termites, of which 38% led to attack. Sixty‐one percent of these attacks led to termite exclusion from the plants. Recruitment and patrolling were highest when ants fed upon nectaries providing sugar + amino acids, the most nutritious food. This increase in recruitment and patrolling led to higher encounter rates between ants and termites, more frequent attacks, and faster and more complete termite removal. Our results are consistent with the hypothesis that plant biotic defense is mediated by resource quality. We highlight the importance of qualitative differences in nectar composition for the outcome of ant–plant interactions. Abstract in Portuguese is available with online material.     

Improvement of dry matter digestibility of water hyacinth by solid state fermentation using white rot fungi

Feeding value of water hyacinth biomass colonized by three species of white rot fungi during solid-state fermentation was investigated. All three organisms proved to be efficient degraders and enhanced dry matter digestibility. Loss of organic matter was maximum (23.6+/-0.1% dry wt) after 48 days by P. ostreatus. C. indica showed maximum cellulose degradation (18.5+/-0.1% dry wt) than other two fungi after 48 days of incubation. In all cases, an extensive removal of hemicellulose at the initial growth period and a delayed degradation of lignin were observed. Hemicellulolysis was maximum (46.3+/-0.1% dry wt) by C. indica, but delignification (14.2+/-0.2% dry wt) by P. sajor-caju after 48 days. The amount of reducing sugar in the degraded biomass decreased at early stages, but increased as degradation progressed in all three cases (maximum 1.1+/-0.05% dry wt after 48 days by C. indica). Soluble nitrogen content increased only during 16-32 days of incubation (highest 1.1+/-0.1% dry wt after 32 days by P. sajor-caju). Crude protein of the bioconverted biomass increased gradually up to 32 days but decreased thereafter (maximum 10.3+/-0.1% dry wt after 32 days by P. sajor - caju). Per cent change in in vitro dry matter digestibility of degraded substrates enhanced gradually after 8 days and reached maximum after 32 days but thereafter decreased (highest + 20.4+/-0.3% dry wt by P. sajor-caju). The results demonstrated the efficient degrading capacity of the test fungi and their potential use in conversion of water hyacinth biomass into mycoprotein-rich ruminant feed, more so by P. sajor-caju.     

藏羚羊冷季对干物质的消化效率

藏羚羊（Pantholops hodgsoni）为青藏高原特有物种,也是世界上最为珍贵和稀有的物种之一。作为青藏高原野生食草动物的典型代表,藏羚羊种群也是构成青藏高原自然生态系统极为重要的组成部分。藏羚羊独特的体态和生理结构,对研究生物适应与进化,尤其是研究高原条件下的生物适应与进化,维护高原地区生态平衡均有极为重要的意义（郑中朝和李宏,2002）。对藏羚羊牧草利用特征的研究对其营养生态学的研究具有重要的科学价值。本文采用藏羚羊饲草中酸不溶灰分作为内源指示剂,对其冷季牧草消化率进行了初步研究,现将结果予以报道。     

Ability of canine termite detectors to locate live termites and discriminate them from non-termite material

Dogs were trained to detect Eastern subterranean termites, Reticulitermes flavipes (Kollar), using the United States Customs method of scent detection dog training modified with a food reward. Dogs were tested with various numbers of Eastern subterranean termites placed in vented PVC containers. Trained dogs were 95.93% accurate in finding > or = 40 Eastern subterranean termite workers (positive indications) and incorrectly indicated the presence of termites in 2.69% of the containers without termites. Multiple species of termites [dark southern subterranean, R. virginicus (Banks); Formosan subterranean, Coptotermes formosanus Shiraki; powderpost, Cryptotermes cavifrons Banks; and southeastern drywood termites, Incisitermes snyderi (Light)], were similarly evaluated. Dogs trained to locate Eastern subterranean termites were also 100% accurate in finding dark southern subterranean termites, 98.89% accurate in finding Formosan subterranean termites, 97.33% accurate in finding powderpost termites, and 88.89% accurate in finding southeastern drywood termites. Dogs were able to discriminate live termites from non-termite material. Trained dogs' false response rate was 25.33% to Eastern subterranean termite-damaged wood, 6.67% to American cockroaches, Periplaneta americana (L.), and 2.67% to Florida carpenter ants, Camponotus floridanus Buckley.     

五种丛生状棕榈植物叶热值的月变化研究

对5种丛生状棕榈植物一欧洲棕、细叶棕竹、小箬棕、玲珑椰子、缨络椰子的叶片热值和灰分含量的月变化进行了研究,结果表明,5种植物具有较高的灰分含量,但灰分含量的月变化趋势各不相同;欧洲棕、细叶棕竹、小箬棕3种植物干重热值的月变化趋势有些差异,同属的缨络椰子、玲珑椰子干重热值的月变化趋势基本相似;缨络椰子、小箬棕的干重热值与灰分含量具有显著的线性相关(P<0．05),而其余3种植物的干重热值与灰分含量相关性不显著(P>0．05);从去灰分热值的月变化来看,细叶棕竹与小箬棕,缨络椰子与玲珑椰子的月变化趋势相似。     

Defecation, apparent absorption efficiency, and the importance of water obtained in the food for water balance in captive brown long-eared (Plecotus auritus) and Daubenton's (Myotis daubentoni) bats

Mean apparent dry mass absorption efficiency by P. auritus fed on mealworms was 0.853 (S.D.=0.4, n=43). Mean apparent energy absorption efficiency by P. auritus and M. daubentoni fed on mealworms was 0.90 (S.D.=0.007, n=8). The mean energy content of mealworms was 28.6 kJ.g^-1 dry mass (S.D.=1.1, n=8), and that of faeces was 19.5 kJ.g^-1 (S.D.=0.7, n=8) in P. auritus and 19.9 kJ.g^-1 (S.D.=1.3, n=8) in M. daubentoni . Water content of mealworms was 61.1% wet mass (S.D.=1.4, n=173); water content of faeces was 73.3% in P. auritus (S.D.=6.8, n=76) and 72.3% (S.D.=7.0, n=42) in M. daubentoni . Oven-dried mealworms consisted of <1% ash, <1% carbohydrate, 31% lipid and 39% protein. We suggest that the dry mass unaccounted for (28%) represented chitin, of which 59% was apparently absorbed during digestion. Apparent absorption by mass of both lipid and protein by P. auritus fed on mealworms was greater than 90%. Cumulative post-prandial defecation was sigmoidal in both bat species with 50% (by mass) of faeces being voided within 4 h and 95% within 12 h of feeding. On the basis of previous measurements, using doubly-labelled water, of daily energy expenditure and water flux in free-living P. auritus , we predict that water intake via the food, as free water and as potential metabolic water, represents 20 to 40% of total daily water flux for P. auritus during lactation in the wild.     

Ecophysiology and nutritional niche of the bilby (Macrotis lagotis), an omnivorous marsupial from inland Australia: a review

The bilby (Macrotis lagotis) is a small omnivorous marsupial that was once widespread but is now restricted to the most arid margins of its former range. It feeds on a mixture of invertebrates (mainly ants and termites) and plant material (mainly seeds and bulbs), most of which is below ground. Measurements of the energy and water requirements of free-living bilbies and of the maintenance nitrogen requirements of captive animals provided the basis for an explanation for its continued survival in the Australian arid zone. Measurements of the mean retention times of inert markers for the solute and particulate phases of digesta revealed no selective retention of solutes and small particles in the caecum. Lack of selective digesta retention in the bilby hindgut helps to explain why the plant component of their diet consists predominantly of seeds and bulbs of relatively low fibre content. This is in contrast to the stems and leaves eaten by other bandicoots, all of which appear to have a colonic separation mechanism that not only selectively retains small particles in the caecum but also facilitates the passage of large fibrous particles through the colon. The ability of the bilby to survive in the Australian arid zone is related to low water and nitrogen requirements and the abundance of ants, termites, bulbs and seeds. Foraging efficiency is maximised by exploiting the underground nests of seed-harvesting ants.     

Metabolic physiology of the numbat (Myrmecobius fasciatus)

The numbat (Myrmecobius fasciatus) is unique amongst marsupials as it is exclusively diurnal, feeds only on termites and is semi-fossorial. This study examines the thermal and metabolic physiology of the numbat to determine if its physiology reflects its phylogeny, diet and semi-fossorial habit. Numbats (mean adult body mass 552 g) were able to regulate body temperature at ambient temperatures of 15-30 degrees C, with a body temperature at thermoneutrality (30 degrees C) of 34.1 degrees C. The thermoneutral body temperature was not significantly different from that predicted for an equivalent-sized marsupial. Basal metabolic rate, measured at 30 degrees C, was 0.389 +/- 0.025 ml O(2) g(-1) h(-1), and was slightly but not significantly lower at 82.5% of that predicted for a typical marsupial of equivalent body mass. Metabolic rate increased with decreasing ambient temperatures below 30 degrees C. Patterns of metabolic cycling observed for completely inactive numbats at ambient temperatures below 30 degrees C are likely to be related to sleep phase. Wet thermal conductance of 1.94 J g(-1) h(-1) degrees C(-1) (at 30 degrees C) was 131% of that predicted for a marsupial. Evaporative water loss of the numbat remained constant below the thermoneutral zone (<30 degrees C) at approximately 0.6 ml g(-1) h(-1), only 47.4% of that predicted for a marsupial. It increased to 1.01 +/- 0.16 ml g(-1) h(-1) at an ambient temperature of 32.5 degrees C. The thermal and metabolic physiology of the numbat is generally similar to that expected for other marsupials, and is also comparable to that of termitivorous placental mammals. Thus the reduction in body temperature and basal metabolic rate of placental termitivores is a "marsupial-like" low energy turnover physiology, and the numbat being a marsupial already has an appropriate physiology to survive exclusively on a low energy diet of termites.     

Comparative use of four different marker systems for the estimation of digestibility and low food intake in a group of captive giraffes (Giraffa camelopardalis)

In a feeding trial with four captive giraffes, nutrient digestibility was determined using four different marker systems. Although cobalt‐ethylenediaminetetraacetic acid proved to have no utility as a digestibility marker in this study, reasonable values could be obtained using C₃₆ n‐alkane, acid detergent lignin, and acid insoluble ash as markers. A comparison of methods and literature data suggests that the values derived from the C₃₆ n‐alkane assay are the most reliable absolute values. Apparent digestibility ranges thus determined were 63.5–74.3% for dry matter, 73.4–82.4% for crude protein, 49.9–62.2% for neutral detergent fiber, and 49.7–63.7% for acid detergent fiber. However, digestibility data gained by the ADL method provided the most stringent inter‐individual comparisons. It is concluded that both alkanes and lignin can be used for giraffe digestibility studies. These captive giraffes ingested a smaller quantity of food than has been reported for other giraffes from both the wild and other zoos. Energetic calculations showed that these animals might be on the brink of an energy deficit. A similar situation has been described at least once before in captive giraffes, and the results are of direct relevance to the peracute mortality syndrome, a condition of captive giraffes in which severe depletion of body fat stores occurs. Reasons for the seemingly low food intake could not be elucidated, but observations suggested that these giraffes were ready to ingest more if more palatable or suitable food was offered. Monitoring food intake in other giraffe groups and designing a diet that is both palatable and nutritious are important objectives of captive giraffe management. Zoo Biol 20:315–329, 2001. © 2001 Wiley‐Liss, Inc.     

Agri-environmental grass hay: nutritive value and intake in comparison with hay from intensively managed grassland

Chemical composition, digestibility, nutritive value and intake of hay from an agri-environmental management (EH) were compared with those from hay (Lolium perenne) from an intensive management (IH). IH was of low to moderate quality because of unfavourable weather conditions. EH was harvested mid-June of 2000 (EH1) and 2001 (EH2) on the same sward that had not received mineral fertilizer for 10 years. The EH was characterized by a species-rich botanical composition. On average, it had lower contents of protein (32%), NDF (9%) and ash (35%), and a higher concentration of water-soluble carbohydrates (117%) than IH. Digestibility of dry and organic matter, determined with sheep, was not different between IH and EH and averaged 59 and 63%, respectively. Crude fibre and NDF digestibility were lower in EH (58 and 57%, respectively) than in IH (70 and 69%, respectively). Net energy value for lactation did not differ between IH and EH and amounted to 4.78 MJ per kg DM. True protein digested in the small intestine and rumen degraded protein balance were lower in EH (63 and -60 g per kg DM) than in IH (71 and -33 g per kg DM). Intake of hay was investigated in Holstein-Friesian heifers and Belgian Blue double-muscled heifers (mean BW 280 +/- 22 kg and 269 +/- 21 kg, respectively), and in Belgian Blue non-lactating and non-pregnant double-muscled cows (initial BW 642 +/- 82 kg), using a cross-over design. Hay was freely available. It was supplemented with 1 kg concentrate daily. Dry matter intake from hay was higher for EH than for IH in heifers (4% and 13%, respectively in Holstein-Friesian and Belgian Blue heifers) and in cows (22%). Hay from an agri-environmental management may be used for low-performing animals, as energy intake only exceeded maintenance requirements by 20 to 35%. Several characteristics of EH were different between years, such as dry matter digestibility, net energy value for lactation and fermentable organic matter content.